Electrochemical oxidation has been proposed as a remediation method for chlorinated phenols but is hampered by anode fouling. In this work we explore the mechanism of anode fouling by chlorinated phenols, compare structure vs reactivity for phenols differing in the extent of chlorination, and relate the efficiency of oxidation to the mechanism of oxidation at different electrode types. Linear sweep voltammograms at a Pt anode at several concentrations, sweep rates, and pH were interpreted in terms of deposition of oligomers on the anode surface. Chronopotentiometry at Pt showed that the oxidation potentials of the chlorinated phenol congeners ranged from +0.6 to +1.3 V vs SHE in the pH range 2-12; four electrons are transferred for mono-and trichlorophenols and two for pentachlorophenol. Passivation increased in parallel with the uncompensated resistance of the solution and occurred only at potentials at which water is oxidized, suggesting that the formation of the oligomer film involves attack of hydroxyl radicals on electrochemically oxidized substrate. Seven chlorinated phenols were electrolyzed at PbO 2 , SnO 2 , and IrO 2 anodes. Relative reactivities of congeners were anode-dependent, due to different mechanisms of oxidation: direct electron-transfer oxidation at PbO 2 and hydroxyl radical attack at SnO 2 and IrO 2. At current densities < 0.1 mA cm -2 , current efficiencies > 50% could be achieved with 4-chlorophenol at all three anodes.

Palladium-and Rh-plating of the graphite furnace has been evaluated as a method of introducing the metallic form of Pd and Rh for chemical modification in electrothermal atomic absorption spectrometry. It is shown that by electroplating Pd and Rh onto the inner surface of the tube, the pretreated graphite surface may resemble the behaviour of the corresponding modifier. The resulting metallic layer is very effective in inhibiting the loss of volatile elements (e.g., As and Se), as well as reducing the influence of oxide and carbide formation (e.g., Si). The advantage of the proposed procedure of introduction of a solid chemical modifier is that the pretreated tubes exhibit an extended analytical lifetime for the determination of As and Se, up to 80 and 160 firings in the presence of Pd and Rh, respectively. In the case of Si the Rh-plated graphite tube could last for about 100 firings.

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